Tappet



May 30, 1967 R. F. ABELL, JR

TAPPET Filed May 27, 1966 INVENTOR. FOY Fl ABELL,J/?.

ATTOQMEYS United States Patent Ohio Filed May 27, 1966, Ser. No. 553,548 9 Claims. (Cl. 123-90 This invention relates, generally, to valve tappets for use with internal combustion engines.

In prior art operating valve train linkages for internal combustion engines, it was customary to supply oil to the rocker arm by means of the engine lubricating pump. Various improved methods of lubricating the rocker arm have been suggested. Most of the previous proposals have utilized the valve train push rod as a conduit for conducting oil from the valve tappet or lifter to the rocker for purposes of lubrication. These previous proposals incorporated valving means in the tappet or lifter to control the flow of lubricant to the rocker arm to thereby preclude either an over supply of oil to the valves at high operating speeds (with consequent loss through the valve guides to the engine cylinders) or a low supply of oil at low speeds. As an example of a prior art proposal utilizing the push rod as a means of conducting lubricant from the lifter or tappet to the rocker arm, reference is made to the Papeuguth Patent No. 2,818,050. Papenguth teaches a hollow push rod and a floating plate-like valve adapted to restrict oil flow into the push rod for delivery to the rocker arm during operation of the valve train. Although the Papenguth structure is disclosed in conjunction with a hydraulic valve lifter, the principles of metering lubricant through a hollow push rod is equally applicable to both mechanical valve lifters and tappets.

Prior proposals for lubricating the rocker arm by means of conducting the oil through the valve train push rod have, therefore, taken many forms as different valving or metering structures have been introduced in the tappet or lifter. These proposals have not only raised the cost of the tappet or lifter due to the increased number of machined parts in the tappet but have also decreased the reliability of the tappet or lifter because of the probability that the valving structure will not function properly when assembled.

It is an object of this invention, therefore, to provide a valve tappet in which a simple and inexpensive metering means is provided to control the flow of lubricant from the engine block to the rocker arm by means of a hollow push rod.

It is a further object of this invention to provide an oil metering means in a tappet that does not require the addition of parts in the tappet.

It is a still further object of this invention to provide a tappet with an oil metering means that is reliable and that may be assembled with a minimum of cost.

These and other objects and purposes of this invention will be immediately understood by those acquainted with the design and construction of tappets upon reading the following specifications and the accompanying drawings in which:

FIGURE 1 is an elevational view, partly in section, of a pair of tappets constructed according to this invention in a V-8 internal combustion engine block.

FIGURE 2 is a sectional view of a tappet constructed according to one embodiment of this invention.

FIGURE 3 is a sectional view of a tappet constructed according to a second embodiment of this invention.

Referring now more particularly to FIGURE 1, there is shown an engine block having a pair of tappets 12 and 14, constructed according to this invention, received in cylindrical bores 16. One end of each of said tappets 12 and 14 includes a cam engaging face 18 adapted to abut cam shaft 20. Cam shaft 20 includes a base circle portion 22 and a lift portion 24. As shown in FIGURE 1, tappet 12 is engaging the base circle portion 22 of cam shaft 20 and tappet 14 is engaging the lift portion 24 of cam shaft 20. Abutting portions of the tappets near the other ends thereof are push rods 26 and 28. Push rods 26 and 28 are adapted to engage suitable rocker arms to complete the valve train linkage from the cam shaft to the valve. Defined in each of the push rods 26 and 28 is a passageway 30 for the purpose of conducting oil from the tappet to the rocker arm to thereby lubricate the points of contact of the push rod and the rocker arm as well as the valve and the rocker arm. As this invention is concerned primarily with the means by which oil flow from the engine to the push rod is metered or controlled, only that portion of the valve train linkage will be described.

As shown in FIGURE 1, tappets 12 and 14 are identical and include a first external annular groove 32 and a second external annular groove 34. Separating grooves 32 and 34 is a cylindrical metering land 36.

Intersecting the cylindrical bores 16 so as to overlie the first groove 32 of each tappet is the engine oil gallery passageway 38. As shown in FIGURE 1, the oil gallery 38 intersects the center line of each of the cylindrical tappet receiving bores 16 of the engine block 10. Gallery 38 is thus parallel to the axis of cam shaft 20.

Reference is now made to FIGURE 2 wherein there is shown a first embodiment of this invention. The tappet structure of FIGURE 2 includes a tappet body 38 having a cam engaging surface 40 at one end thereof. The valve actuating push rod is adapted to be received in a socket element 42 generally defined as a T-shaped element. Socket element 42 is suitably seated on shoulders 44 defined on the interior surface of the tappet body 38. Retaining the socket element 42 in place is a snap ring 46 suitably received in a recess 48 of the tappet body 38. Defined on the exterior surface of the socket element 42 is a generally spherical bearing surface 50 adapted to receive one end of a hollow push rod. Also provided in the socket element 42 is a passageway 54 designed to provide communication between the interior 52 of the tappet body 38 and the passageway of the hollow push rod.

The exterior of tappet body 38 of FIGURE 2 is generally cylindrical and includes a first annular groove 32 and a second annular groove 34. Separating grooves 32 and 34 is a cylindrical land 36. Provided in the tappet body 38 so as to provide communication between the interior 52 of the tappet and the second groove 34 is a radial passageway 56.

Reference is now made to FIGURE 1 wherein the operation of the embodiment of the tappet shown in FIG- URE 2 will be described. It is to be noted that the exterior configuration of the tappets 12 and 14 as shown in FIG- URE 1 is identical to the exterior configuration of the tappet as shown in FIGURE 2. During operation of an internal combustion engine, oil is caused to flow in the oil gallery 38 at a pressure of approximately 45 to 50 psi. Because groove 32 is in communication with the gallery 38, an oil ring or reservoir is caused to be collected in the groove 32. The groove 32 provides two functions in the operation of the tappet of this invention. Because the gallery 38 intersects the center line of the tappet receiving bores 16, the first function of the groove 32 is to provide a communication means from one cylindrical bore 16 to an adjacent cylindrical bore 16. Thus oil entering one portion of cylindrical bore 16 may be conducted halfway around the exterior of the tappet in groove 32 and continue in Patented May 30, 1967 the gallery 38 to an adjacent cylindrical bore 16. A second function of the groove 32 is to provide a ring of oil at uniform pressure so that a controlled flow of oil may be established to the rocker arm.

The control means of this invention is the cylindrical metering land 36. By carefully controlling the clearance between the metering land 36 and the internal walls of the engine block defining the bore 16, a controlled flow of oil may thereby be established to the rocker arm. Oil is thus caused to flow from the first groove 32 across the metering land 36 into the second groove 34. Groove 34 might appropriately be called a collecting groove as a ring of oil is thereby established in the groove 34. The oil in groove 34 may thereafter be conducted through the radial passageway 56 into the interior of the tappet. As is evident from FIGURE 2, a flow of pressurized oil into the passageway 56 will eventually fill the interior 52 of the tappet body 38. After filling of the interior of the tappet a continued input of oil into the tappet will result in a flow through the passageway 54 of the socket element 42 and thereafter into the hollow push rod to the rocker arm.

In FIGURE 3 there is shown a second embodiment of this invention. Wherein it is possible, like reference characters will be used in FIGURE 3 as were used in FIGURES 2 and 1. The embodiment of FIGURE 3 includes a tappet body 58 having a generally external cylindrical surface provided with a first annular groove 32 and a second annular groove 34. Separating annular grooves 32, 34 is a cylindrical land 36. The external configuration of the tappet embodiment of FIGURE 3 is therefore identical to the external configuration of the tappet embodiment of FIGURE 2. Tappet body 58 of FIGURE 3 includes a cam engaging face 40 at one end thereof and a recessed portion 60 at the other end thereof. Recess 60 extends approximately midway into the tappet body 58 and is terminated by a generally spherical bearing surface 62. Bearing surface 62 is adapted to receive one end of a hollow push rod in a manner similar to the bearing surface 50 of FIGURE 2. To provide communication between the bearing surface 62 and the second annular groove 34 on the exterior surface of tappet body 581there is provided an axial passageway 64 which intersects a radial passageway 56. The operation of the tappet embodiment of FIGURE 3 is similar to that described with reference to the embodiment of FIG- URE 2. Thus the oil gallery 38 deposits a ring of oil in the first annular groove 32. Due to the slight clearance between the cylindrical land 36 and the Walls of the cylindrical bore 16, oil is caused to flow from the first annular groove 32 to the second annular groove 34 wherein it is conducted by means of passageway 56 and passageway 64 to the bearing surface 62. Because the oil is pressurized it will thereafter be conducted through the hollow push rod to the rocker arm to lubricate the points of contact of the hollow push rod and the rocker arm as well as the valve and the rocker arm.

Since the function of the cylindrical land surface 36 is to meter or control the flow of oil from the annular groove 32 to the annular groove 34, the oil gallery must be positioned with respect to the tappet such that at no time during the operation of the valve actuating mechanism the oil gallery is in direct communication with the second annular groove 34. Obviously, if the oil gallery directly communicates with the second annular groove 34, the means to control or meter the flow of oil will have been by-passed and, thus, an uncontrolled flow will be established between the oil gallery and the hollow push rod. Such uncontrolled flow is undesirable in that excessive oil is thereby conducted to the rocker arm. Considering FIGURE 1, therefore, it may be seen that the oil gallery 38 is positioned such that at all times during reciprocating movement of the tappet the gallery will partly overlie the first annular groove 32 without overlying the second annular groove 34. Thus considering tappet 12 of FIGURE 1 it will be seen that as tappet 12 is at rest on the base circle 22 of the cam shaft 20, the oil gallery 38 almost completely overlies the first annular groove 32. Considering tappet 14 of FIG- URE 1, it may be seen that as said tappet is at rest on the lift portion 24 of the cam shaft 20, oil gallery 38 at least partially overlies the annular groove 32 while at the same time overlying a portion of the cylindrical land 36. A portion of the cylindrical land 36 is therefore still available for purposes of metering flow of oil from groove 32 to groove 34. As was previously pointed out, should a portion of oil gallery 38 at least partially overlie the second annular groove 34, direct communication will thereby be established between the oil gallery and the second annular groove with the result that the metering structure of the tappet will have been by-passed and an uncontrolled flow of oil to the rocker arm established.

The amount of oil that will flow past the metering land 36 during operation of the internal combustion engine is a function of (a) the engine oil pressure, (b) the clearance between the metering land and the walls defining the cylindrical bore 16, (c) the width of the meter land 36, (d) the viscostiy and cleanliness of the oil and (e) the external diameter of the tappet. Operating oil pressure in an internal combustion engine is approximately 45-50 p.s.i. With a tappet diameter of 0.75-1.00 inch, it has been found that a suitable flow of oil may be established to the rocker arm with a metering land band width of inch, and a clearance of .0015 inch between the metering land and the walls of the tappet receiving bore. Where an internal combustion engine operates at less than 45-50 p.s.i. it has been found that the band width of the metering land must be reduced. Thus at an oil pressure of 30 p.s.i. it has been found that the optimum band width of the metering land is approximately inch. The external diameter of the tappet and the clearance between the metering land and the tappet receiving bore are interrelated. Thus as the tappet diameter is changed, the clearance between the metering land the walls of the cylindrical bore receiving the tappet must also be changed. Considering a range of tappet diameters from 0.75 to 1.00 inch, a suitable clearance between the metering land and the tappet receiving bore will'be included within the range of 0005-.0025 inch. With a clearance less than .0005 inch the tappet may bind in the tappet bore of the engine block when heated. With -a clearance greater than .0025 inch, flow conditions across the land 36 will approach uncontrolled flow as when the oil gallery is in direct communication with the push rod. Optimum conditions of metering land clearance have been found to exist at approximately the midpoint of the range .0005-.0025 inch or approximately .0015 inch.

The above figures are given for purposes of illustration only and should not be considered as limiting this invention.

The heart of the oil metering structure of this invention is therefore the metering land 36 of FIGURES 2 and 3. A carefully controlled clearance must therefore exist between the metering land 36 and the cylindrical tappet receiving bore of the engine block. Cylindrical lands 66 and 68 of FIGURES 2 and 3 serve to align the tappet in the tappet receiving bore as well as provide guide means for reciprocation of the tappet in the tappet receiving bore during operation of the valve train. The external diameter of the metering land 36 may be equal to or less than the external diameter of cylindrical lands 66 and 68. Production of the tappet of this invention may be greatly simplified, of course, if the external diameter of land 36, 66 and 68 are equal. In such an instance, it may be expected that oil in groove 32 will leak past both the cylindrical land 66 as well as the metering land 36. Of course, oil that flows past the metering land 36 will be conducted to the rocker arm via the hollow push rod. Oil leaking past the cylindrical land 66 will tend to collect in the upper portion of the tappet body and thereafter will flow drical lands 66 and 68 and the tappet receiving bore may be reduced. In this instance, the external diameter of the cylindrical lands 66 and 68 will be greater than the external diameter of the metering land 36. Thus, this invention should not be considered limited to a tappet wherein the external diameter of the various cylindrical lands is constant. The critical clearance for purposes of metering oil to the rocker am is the clearance between the metering land and the walls of the tappet receiving bore. Should leakage of oil past the upper and lower cylindrical lands of the tappet become excessive then these clearances may be reduced without affecting the clearance between the metering land and the tappet receiving bore.

Nor should this invention be considered limited to the environment in which a tappet is received in a cylindrical bore in an engine block. Where, for instance, tolerances in the manufacturing of the engine block are excessive, it may prove impractical to achieve a regulated clearance at the oil metering land of the tappet due to the wide fluctuations in the internal diameter of the tappet receiving bore. In such an instance it is conceivable that a cylindrical bore liner may be utilized between the cylindrical bore of the engine block and the tappet to thus achieve a controlled oil metering clearance between the liner and the tappet. Communication between the oil gallery and the tappet groove may be established by means of a passageway in the liner.

I claim:

1. In a lubricating system for an engine or the like including a reciprocatedly actuated tappet, a rocker, and a hollow push rod drivingly connecting said rocker to the tappet and constituting an oil conductor between said rocker and said tappet, the combination of:

an engine block having a wall provided with at least one cylindrical tappet guide means therein,

a fluid passageway in said engine block,

a cylindrical tappet disposed within said guide means,

said tappet including,

a bearing surface to receive a hollow push rod,

a cam engaging face to abut a valve actuating cam,

a first groove on the exterior surface of said tappet,

a second groove on the exterior surface of said tappet separated from said first groove by a flow metering means,

first communication means between said second groove and said hollow push rod,

second communication means between said fluid passageway and said first groove for providing direct communication only between said fluid passageway and said first groove, while providing indirect communication to said second groove only via said flow metering means.

2. The invention of claim 1 in which said tappet guide means is defined by a cylindrical bore in said engine block and said second communication means is defined by an opening in the wall defining said cylindrical bore, at least a portion of said opening overlying said first groove of said tappet at all times during reciprocation of the tappet.

3. The invention of claim 1 in which said first communication means is defined by a passageway intersecting said second groove and said bearing surface.

4. The invention of claim 1 in which said flow metering means is further defined by a cylindrical land surface between said first groove and said second groove, the clearance between said cylindrical land surface and said guide means ranging from .0005 to .0025 inch.

5. The invention of claim 1 in which said flow metering means is further defined by a cylindrical land surface between said first groove and said second groove, the clearance between said cylindrical land surface and said guide means being .0015 inch.

6. The invention of claim 1 further defined in that the distance between said first groove and said second groove is at least A; inch.

7. The invention of claim 1 in which said bearing surface of said tappet is further defined by a T-shaped socket element seated on shoulders of an internal wall of said tappet, said socket element defining a bearing surface to receive one end of a hollow push rod, and said first communication means is further defined by a passageway in said socket opening into the interior of said tappet and a passageway in said tappet extending from said second groove to said interior.

8. The invention of claim 1 in which said bearing surface is defined as an integral part of said tappet recessed from one end thereof and said first communication means is further defined as a passageway in said tappet.

9. In an internal combustion engine the combination of an engine block having a wall provided with at least one cylindrical bore therein,

a cylindrical valve tappet disposed within said bore,

said tappet including,

a cylindrical tappet body with a cam engaging face on one end thereof and a recessed portion at the other end thereof,

a bearing surface on said tappet body at the base of said recessed portion, said bearing surface adapted to receive one end of a hollow push rod,

a first annular groove on the exterior surface of said tappet,

a second annular groove on the exterior surface of said tappet spaced apart from said first annular groove by a cylindrical land surface of said tappet body,

a passageway from said second annular groove to said bearing surface, said passageway opening into both said second annular groove and said bearing surface so as to overlie at least a portion of the end of said hollow push rod,

an oil gallery passageway in said engine block opening into said cylindrical bore so as to overlie only said first annular groove of said tappet at all times during reciprocation of said tappet, whereby communication to said second annular groove is only via said cylindrical land surface,

the clearance between said cylindrical land surface and said cylindrical bore being in the range 0.0005 to 0.0025 inch to permit a controlled flow of oil from said oil gallery passageway to said hollow push rod.

References Cited UNITED STATES PATENTS 2,145,484 1/1939 Johnson 12390 2,682,865 7/1954 Voorhies 123-90 3,089,473 5/ 1963 Kueny 123-90 3,262,434 7/1966 Kuchen et a1. 12390 FOREIGN PATENTS 925,866 3/ 1955 Germany.

MARK NEWMAN, Primary Examiner.

AL LAWRENCE SMITH, Examiner. 

1. IN A LUBRICATING SYSTEM FOR AN ENGINE OR THE LIKE INCLUDING A RECIPROCATEDLY ACTUATED TAPPET, A ROCKER, AND A HOLLOW PUSH ROD DRIVINGLY CONNECTING SAID ROCKER TO THE TAPPET AND CONSTITUTING AN OIL CONDUCTOR BETWEEN SAID ROCKER AND SAID TAPPET, THE COMBINATION OF: AN ENGINE BLOCK HAVING A WALL PROVIDED WITH AT LEAST ONE CYLINDRICAL TAPPET GUIDE MEANS THEREIN, A FLUID PASSAGEWAY IN SAID ENGINE, BLOCK, A CYLINDRICAL TAPPET DISPOSED WITHIN SAID GUIDE MEANS, SAID TAPPET INCLUDING, A BEARING SURFACE TO RECEIVE A HOLLOW PUSH ROD, A CAM ENGAGING FACE TO ABUT A VALVE ACTUATING CAM, A FIRST GROOVE ON THE EXTERIOR SURFACE OF SAID TAPPET, A SECOND GROOVE ON THE EXTERIOR SURFACE OF SAID TAPPET SEPARATED FROM SAID FIRST GROOVE BY A FLOW METERING MEANS, FIRST COMMUNICATION MEANS BETWEEN SAID SECOND GROOVE AND SAID HOLLOW PUSH ROD, SECOND COMMUNICATION MEANS BETWEEN SAID FLUID PASSAGEWAY AND SAID FIRST GROOVE FOR PROVIDING DIRECT COMMUNICATION ONLY BETWEEN SAID FLUID PASSAGEWAY AND SAID FIRST GROOVE, WHILE PROVIDING INDIRECT COMMUNICATION TO SAID SECOND GROOVE ONLY VIA SAID FLOW METERING MEANS. 